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Altair is a white main sequence star of spectral class A7 V-IV<ref name="simbad">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=alf+aql</ref>.  The star is estimated to have some 1.7 times the mass of our sun, and 1.8 times its diameter<ref>Imaging the Surface of Altair, J. Monnier et al., Science 317, #5836 (July 20, 2007), pp. 342–345</ref>.  Altair is also considerably brighter, with 10.7 times the visual luminosity of the Sun, even though much of the [[radiation]] from Altair is in the [[ultraviolet]].

Altair is a white main sequence star of spectral class A7 V-IV<ref name="simbad">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=alf+aql</ref>.  The star is estimated to have some 1.7 times the mass of our sun, and 1.8 times its diameter<ref>Imaging the Surface of Altair, J. Monnier et al., Science 317, #5836 (July 20, 2007), pp. 342–345</ref>.  Altair is also considerably brighter, with 10.7 times the visual luminosity of the Sun, even though much of the [[radiation]] from Altair is in the [[ultraviolet]].

Altair is a young, [[metallicity|metals-rich star]].  Using [[metallicity]], the star is estimated to be twice as enriched as the [[Sun]], based on its abundance of [[iron]]<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1992A%26AS...95..273C</ref>.  Dust has been also detected orbiting Altair<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999A%26A...350..603H&db_key=AST&high=3faa46c3cc22628</ref>.  The star itself may only be a few hundred million years old but will quickly exhaust its hydrogen fuel within a billion years due to its size and temperature.   

Altair is a young, [[metallicity|metals-rich star]].  Using [[metallicity]], the star is estimated to be twice as enriched as the [[Sun]], based on its abundance of [[iron]]<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1992A%26AS...95..273C</ref>.  Dust has been also detected orbiting Altair<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999A%26A...350..603H&db_key=AST&high=3faa46c3cc22628</ref>.  The star itself may only be a few hundred million years old but will quickly exhaust its hydrogen fuel within a billion years due to its size and temperature.

 

Altair has also be recently identified as [[variable star]], and thus has the New Suspected Variable designation '''NSV 24910'''.  The change in its magnitude is not possible to detect by the unaided eye.  The variation occurs in nine different periods ranging from nine hours to a mere 50 minutes in length, and changes by only a few thousandths of a magnitude.<ref>http://stars.astro.illinois.edu/sow/altair.html</ref>

One interesting aspect about Altair is the unusually fast rotational speed of 210 kilometers per second.  The star rotates so quickly that it completes a rotation in some 10.4 hours.  In comparison, the [[Sun]] takes 25.4 days to complete a rotation.  As a result of this rapid rotation, the star is most likely shaped like a flattened ellipsoid, with an equatorial diameter some 14 percent greater then the diameter at the poles<ref>Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry, Gerard T. van Belle, David R. Ciardi, Robert R. Thompson, Rachel L. Akeson, and Elizabeth A. Lada, Astrophysical Journal 559 (October 1, 2001), pp. 1155–1164, doi:10.1086/322340, Bibcode: 2001ApJ...559.1155</ref>.

One interesting aspect about Altair is the unusually fast rotational speed of 210 kilometers per second.  The star rotates so quickly that it completes a rotation in some 10.4 hours.  In comparison, the [[Sun]] takes 25.4 days to complete a rotation.  As a result of this rapid rotation, the star is most likely shaped like a flattened ellipsoid, with an equatorial diameter some 14 percent greater then the diameter at the poles<ref>Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry, Gerard T. van Belle, David R. Ciardi, Robert R. Thompson, Rachel L. Akeson, and Elizabeth A. Lada, Astrophysical Journal 559 (October 1, 2001), pp. 1155–1164, doi:10.1086/322340, Bibcode: 2001ApJ...559.1155</ref>.